Pressure ulcers are a costly problem affecting patients undergoing acute or chronic treatment. Damage to localised areas of skin and underlying tissue can result from decreased perfusion to the affected areas due to pressure, sheer force, and/or friction. For example, the average sacral pressure on standard hospital mattresses is around 100-150 mmHg, while normal capillary filling pressure is around 32 mmHg such that even patients without vascular disease are at risk of developing ulcers.
The effect of pressure on regional perfusion has been widely investigated and it appears that localised pressure must be removed to decrease the incidence of ulcers.
There are several important risk factors which lead to decreased skin perfusion, or which directly damage the skin, the most significant of which is immobility leading to increased pressure on bony prominences. Other risk factors include incontinence (leading to skin maceration and increased likelihood of damage due to friction), age, malnutrition, and female gender.
Risk assessment is an important preliminary step to determining and instigating appropriate prevention and/or treatment regimes. However, ulcer risk assessment is difficult because there is little evidence that the available tools for assessment of risk are reliable or valid. The Braden scale, the Norton Risk Assessment score and the Waterloo Risk Assessment tool are examples of risk assessment tools utilised clinically in various countries.
The reliability of these assessment tools depends on the individual who takes the readings, and appropriate risk cut-off scores, among other things (see Australian Wound Management Association (2001) “Clinical Practice Guidelines for the Prediction and Prevention of Pressure Ulcers (abridged version)”). Despite these potential stumbling blocks, risk assessment is important because the appropriate prevention techniques depend on risk level, and both over and under-treatment are costly.
Several prevention techniques have been suggested, including the use of Australian Medical Sheepskin, ‘low-tech’ surfaces such as foam mattresses, ‘high-tech’ surfaces such as alternating pressure mattresses, and others, for instance, repetitively changing a patient's position and/or turning mattresses over and/or regularly repositioning patients.
Pressure care devices that are currently on the market can, for convenience, generally be divided into ‘low-tech’ and ‘high-tech’ devices. Examples from each group are listed below:
Low-Tech Devices
    I. Standard foam mattresses;    II. Alternative foam mattresses/overlays (eg, high-specification foam, viscoelastic material, convoluted foam, cubed foam). These are conformable and aim to redistribute pressure over a large contact area;    III. Gel-filled mattresses/overlays;    IV. Fluid-filled mattresses/overlays;    V. Fibre-filled mattresses/overlays; and    VI. Air-filled mattresses/overlays.High-Tech Devices    I. Alternating pressure (AP) devices. Typically, the patient lies on a grid of air-filled sacs which sequentially inflate and deflate, relieving pressure at different anatomical sites for short periods;    II. Air fluidised devices. Warmed air is circulated through fine ceramic beads covered by a permeable sheet. These devices allow support over a large contact area;    III. Low air loss (LAL) devices. Typically, patients are supported on a grid of air-filled sacs which are inflated at a constant pressure and between which air can be transferred; and    IV. Turning beds/frames (eg, kinetic or profiling beds). These beds typically either aid manual repositioning of the patient, or reposition the patient by motor-driven turning and tilting.
As can be appreciated, when incorporated into an institution-wide prevention program, including patient risk assessment and attention from trained staff, pressure ulcer prevention becomes costly. Furthermore, when prevention fails, ulcer treatment increases the cost and the length of stay in hospital. Complications of decubitus ulcers include cellulitis, osteomyelitis and sepsis.
Recent estimates from 365 US hospitals report ulcer incidence at 14.8% in hospital patients at a cost of between US$3.6 and US$8.5 billion. Indeed, the incremental cost of pressure ulcers related to hospitalisation for each patient has been estimated at US$12,186.
The low-tech and high-tech devices listed above and other prior art devices used in the treatment and/or prevention of pressure ulcers do not (and cannot) identify a given region of the body and cannot administer different affects and/or treatment regimes to different parts of the body differently or to the same or similar region of the body if the patient moves around the devices or objects with which the devices are associated.
The region or regions of interest typically vary from patient to patient and also depending on the type of treatment that is being administered, and the reasons why the patient is in hospital or at risk of developing pressure ulcers, among other things. For example, a patient who is otherwise well and is having a total hip replacement will require different management compared with a demented patient with peripheral arterial disease.
Indeed, current evidence of the use of the abovementioned devices, and in particular, the mattresses, suggests that none of them are especially efficacious at reducing the incidence of pressure ulcers (McInnes et al (2006) “Support surfaces for pressure ulcer prevention”, Issue 3, The Cochrane Database of Systemic Reviews).
The present inventor has developed an interactive patient system and apparatus that is adaptable for use in a number of clinical and domestic situations.